Epothilones are macrolide compounds that find utility in the pharmaceutical field. For example, epothilones A and B having the structures:
have been found to exert microtubule-stabilizing effects similar to paclitaxel (TAXOL®) and hence cytotoxic activity against rapidly proliferating cells, such as, tumor cells or cells associated with other hyperproliferative cellular diseases, see Bollag et al., Cancer Res., Vol. 55, No. 11, 2325–2333 (1995).
Epothilones A and B are natural anticancer agents produced by Sorangium cellulosum that were first isolated and characterized by Hofle et al., DE 4138042; WO 93/10121; Angew. Chem. Int. Ed. Engl. Vol. 35, No13/14, 1567–1569 (1996); and J. Antibiot., Vol. 49, No. 6, 560–563 (1996). Subsequently, the total syntheses of epothilones A and B have been published by Balog et al., Angew. Chem. Int. Ed. Engl., Vol. 35, No. 23/24, 2801–2803, 1996; Meng et al., J. Am. Chem. Soc., Vol. 119, No. 42, 10073–10092 (1997); Nicolaou et al., J. Am. Chem. Soc., Vol. 119, No. 34, 7974–7991 (1997); Schinzer et al., Angew. Chem. Int. Ed. Eng., Vol. 36, No. 5, 523–524 (1997); and Yang et al., Angew. Chem. Int. Ed. Engl., Vol. 36, No. 1/2, 166–168, 1997. WO 98/25929 disclosed the methods for chemical synthesis of epothilone A, epothilone B, analogs of epothilone and libraries of epothilone analogs. The structure and production from Sorangium cellulosum DSM 6773 of epothilones C, D, E, and F was disclosed in WO 98/22461. FIG. 1 provides a diagram of the biotransformation as described in WO 00/39276 of epothilone B to epothilone F in Actinomycetes species strain SC15847 (ATCC PT-1043), subsequently identified as Amycolatopsis orientalis. 
Cytochrome P450 enzymes are found in prokaryotes and eukaryotic cells and have in common a heme binding domain which can be distinguished by an absorbance peak at 450 nm when complexed with carbon monoxide. Cytochrome P450 enzymes perform a broad spectrum of oxidative reactions on primarily hydrophobic substrates including aromatic and benzylic rings, and alkanes. In prokaryotes they are found as detoxifying systems and as a first enzymatic step in metabolizing substrates such as toluene, benzene and camphor. Cytochrome P450 genes have also been found in biosynthetic pathways of secondary metabolites such as nikkomycin in Streptomyces tendae (Bruntner, C. et al, 1999, Mol. Gen. Genet. 262: 102–114), doxorubicin (Dickens, M. L, Strohl, W. R., 1996, J. Bacteriol, 178: 3389-3395) and in the epothilone biosynthetic cluster of Sorangium cellulosum (Julien, B. et al., 2000, Gene, 249: 153–160). With a few exceptions, the cytochrome P450 systems in prokaryotes are composed of three proteins; a ferredoxin NADH or NADPH dependent reductase, an iron-sulfur ferredoxin and the cytochrome P450 enzyme (Lewis, D. F., Hlavica, P., 2000, Biochim. Biophys. Acta., 1460: 353–374). Electrons are transferred from ferredoxin reductase to the ferredoxin and finally to the cytochrome P450 enzyme for the splitting of molecular oxygen.